refactor inject as a function

Lua/inject.lua

@@ -3,81 +3,85 @@ require "boilerplate"
 require "addrs.init"
 local assemble = require "inject.lips"
 
-if version ~= "M US10" then
-    print("Sorry, inject.lua is unimplemented for your version.")
-    return
+function inject(fn)
+    local asm_dir = bizstring and 'inject/' or './mm/Lua/inject/'
+    local asm_path = asm_dir..fn
+
+    local inject_addr -- seemingly unused region of memory
+    local inject_maxlen -- how much room we have to work with
+    local ow_addr -- the jal instruction to overwrite with our hook
+    local ow_before -- what its value is normally supposed to be
+    if version == 'M US10' then
+        inject_addr = 0x780000
+        inject_maxlen = 0x5A800
+        ow_addr = 0x1749D0
+        ow_before = 0x0C05CEC6
+    else
+        print("Sorry, inject.lua is unimplemented for your game version.")
+        return
+    end
+
+    -- encode our jal instruction
+    local ow_after = 0x0C000000 + math.floor(inject_addr/4)
+    if R4(ow_addr) ~= ow_before and R4(ow_addr) ~= ow_after then
+        print("Can't inject -- game code is different!")
+        return
+    end
+
+    -- decode the original address
+    local ow_before_addr = (ow_before % 0x4000000)*4
+
+    -- set up a header to handle calling our function and the original
+    local header = ("[overwritten]: 0x%08X\n"):format(ow_before_addr)
+    header = header..[[
+            // TODO: optimize for size
+            // TODO: fix case where overwritten function takes 5+ args
+            push    ra
+            push    a0, a1, a2, a3
+            bal     start
+            nop
+            pop     a0, a1, a2, a3
+            jal     @overwritten
+            nop
+            jpop    ra
+    start:
+    ]]
+
+    local inject_words = {}
+    local length = 0
+    local function add_word(line)
+        -- takes assembled code, up to 4 bytes at a time, as hex strings
+        length = length + #line/2
+        table.insert(inject_words, tonumber(line, 16))
+    end
+
+    -- offset assembly labels so they work properly, and assemble!
+    local true_offset = 0x80000000 + inject_addr
+    assemble(header, add_word, {unsafe=true, offset=true_offset})
+    assemble(asm_path, add_word, {unsafe=true, offset=true_offset + length})
+
+    printf("length: %i words", length/4)
+    if #inject_words > inject_maxlen then
+        print("Assembly too large!")
+        return
+    end
+
+    for i, v in ipairs(inject_words) do
+        W4(inject_addr + (i - 1)*4, v)
+    end
+
+    -- finally, write our new jump over the original
+    printf('%08X: %08X', ow_addr, ow_after)
+    W4(ow_addr, ow_after)
+
+    -- force code cache to be reloaded
+    if bizstring then
+        local ss_fn = 'inject temp.State'
+        savestate.save(ss_fn)
+        savestate.load(ss_fn)
+    else
+        m64p.reloadCode()
+    end
 end
 
-local asm_path
-if bizstring then
-    asm_path = "inject/spawn.asm"
-else
-    asm_path = "./mm/Lua/inject/spawn.asm"
-end
-
-local inject_addr, inject_maxlen, ow_addr, ow_before
-inject_addr = 0x780000
-inject_maxlen = 0x5A800
-ow_addr = 0x1749D0
-ow_before = 0x0C05CEC6
---ow_addr = 0x174750
---ow_before = 0x0C05D06A
-
-local ss_fn = 'inject temp.State'
-
--- do it
-
-local ow_after = 0x0C000000 + math.floor(inject_addr/4)
-if R4(ow_addr) ~= ow_before and R4(ow_addr) ~= ow_after then
-    print("Can't inject -- game code is different!")
-    return
-end
-
-local ow_before_addr = (ow_before % 0x4000000)*4
-
-local header = ("[overwritten]: 0x%08X\n"):format(ow_before_addr)
-header = header..[[
-        // TODO: optimize for size
-        // TODO: fix case where overwritten function takes 5+ args
-        push    ra
-        push    a0, a1, a2, a3
-        bal     start
-        nop
-        pop     a0, a1, a2, a3
-        jal     @overwritten
-        nop
-        jpop    ra
-start:
-]]
-
-local inject = {}
-local length = 0
-local add_inject = function(line)
-    length = length + #line/2
-    table.insert(inject, tonumber(line, 16))
-end
-local true_offset = 0x80000000 + inject_addr
-assemble(header, add_inject, {unsafe=true, offset=true_offset})
-assemble(asm_path, add_inject, {unsafe=true, offset=true_offset + length})
-printf("length: %i words", length/4)
-
-if #inject > inject_maxlen then
-    print("Assembly too large!")
-    return
-end
-
-for i, v in ipairs(inject) do
-    W4(inject_addr + (i - 1)*4, v)
-end
-
--- finally, inject over jal
-printf('%08X: %08X', ow_addr, ow_after)
-W4(ow_addr, ow_after)
-
--- force code cache to be reloaded
-if bizstring then
-    savestate.save(ss_fn)
-    savestate.load(ss_fn)
-else
-    m64p.reloadCode()
-end
+inject('spawn.asm')